Why not appropriate, as long as you are ready completely in dark crafts, while working newly on it many times it has being seen that such spells backfire and do cause trouble, besides in some death spells it may backfire too as what peoples name karma stuff, take necessary measures apex, shielding-clensing and just be focused and confident working on it and yes you use have your all bad emotions against u our target, let your mind be full of hatred against him in your spell it rituals you direct all these to your target making a negative impact!
My view on this is this. If someone has done something to me that I am offended by, if there is some way to get justice without magick I will do that. But if that isn't possible I try to follow the christian scripture that says to overcome evil with good. This is hard but I see it as something like this: say a cop does something illegal to me. I know there is no justice in the legal system. I can be reasonably sure he has no conscious about much of anything, so I might send a spell to enhance his conscious, then he would feel guilt. I think something like that is acceptable and in the long run it will do him good even though it will cause him pain and suffering in the begining.
it's true that most of us have the desire to do some harm in retaliation at one time or another, but you also have to be aware that if there were nothing inside us to be stirred up, no one could cause us that kind of anger. So it's equally valid that we examine ourselves before we let our anger dominate us.